Driving support apparatus

ABSTRACT

A driving support apparatus ( 12 ) has: a setting device ( 122 ) for setting a first target position ( 31 ) on the basis of a first sign object ( 21 ), if the first sign object requesting a vehicle ( 1 ) to stop is detected; and a supporting device ( 123 ) for performing a first deceleration control for decelerating the vehicle to a first target speed before the vehicle reaches the first target position, if a second sign object ( 22 ) representing a stop position is detected during a period when the first decelerating control is performed, the setting device sets a second target position ( 32 ) on the basis of the second sign object and the supporting device performs a second decelerating control for decelerating the vehicle to a second target speed before the vehicle reaches the second target position.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.16/011,704 filed Jun. 19, 2018 (allowed), which claims benefit fromJapanese Patent Application No. 2017-144189 filed Jul. 26, 2017. Theentire disclosures of the prior applications are considered part of thedisclosure of the accompanying continuation application, and are herebyincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a technical field of a driving supportapparatus that is configured to perform a driving support forautomatically decelerating a vehicle to a target speed before thevehicle reaches a target position, for example.

BACKGROUND ART

A Patent Literature 1 discloses one example of a driving supportapparatus. Specifically, the Patent Literature 1 discloses the drivingsupport apparatus that is configured to extract a road sign requestingthe vehicle to stop or a stop line (a halt line) from an image ahead of(in front of) the vehicle that is captured by a camera, then tocalculate a stop position (namely, a target position) on the basis ofeither one of the extracted road sign and stop line, and then to stopthe vehicle at the calculated target position.

Note that there is a Patent Literature 2 as another document relating tothe present invention.

CITATION LIST Patent Literature

-   [Patent Literature 1] Japanese Unexamined Patent Application    Publication No. 2005-063398-   [Patent Literature 2] Japanese Unexamined Patent Application    Publication No. 2013-196639

SUMMARY OF INVENTION Technical Problem

It is difficult for the driving support apparatus disclosed in thePatent Literature 1 to balance (achieve) a calculation of theappropriate stop position (namely, a calculation of the stop positionthat is not so away from an actual position of the stop line) and ansecurement of an opportunity to control the vehicle to stop at thecalculated stop position. This is a technical problem for the drivingsupport apparatus disclosed in the Patent Literature 1. The reason isbelow described.

There is a possibility that a position at which the road sign(alternatively, any sign requesting the vehicle to stop) is located isaway from the actual position of the stop line. Thus, if the stopposition is calculated on the basis of the road sign, there is apossibility that the calculated stop position is away from the positionof the actual stop line. On the other hand, the stop line(alternatively, any sign representing the position at which the vehicleshould stop) represents the position at which the vehicle should stop,and thus, there is less possibility that the stop position calculated onthe basis of the stop line is away from the position of the actual stopline. However, the stop line is not always detected. For example, thereis a case where the stop line is not detected although the road sign isalready detected. Thus, the opportunity to calculate the stop positionon the basis of the stop line is limited. Namely, the opportunity tocontrol the vehicle to stop at the stop position calculated on the basisof the stop line is limited.

Moreover, not only the driving support apparatus disclosed in the PatentLiterature 1 but also a driving support apparatus that is configured toperform a driving support for automatically decelerating the vehicle toa target speed before the vehicle reaches the target position has thesame technical problem that it is difficult to balance the calculationof the appropriate target position and the securement of the opportunityto control the vehicle to decelerate to a target speed before thevehicle reaches the target position.

The above described technical problem is one example of the technicalproblem to be solved by the present invention. It is therefore an objectof the present invention to provide, for example, a driving supportapparatus that is configured to perform a driving support forautomatically decelerating a vehicle to a target speed before thevehicle reaches a target position, and especially, that is configured tobalance the calculation of the appropriate target position and thesecurement of the opportunity to control the vehicle by the drivingsupport.

Solution to Problem

One aspect of a driving support apparatus of the present invention is adriving support apparatus having: a setting device that is configured toset a first target position on the basis of a detected first signobject, if the first sign object is detected ahead of a vehicle, thefirst sign object requesting the vehicle to stop or decelerate; and asupporting device that is configured to perform a first decelerationcontrol for decelerating the vehicle to a first target speed before thevehicle reaches the first target position, if a second sign object thatis placed to be associated with the first sign object and thatrepresents a position at which the vehicle should complete stopping ordecelerating is detected ahead of the vehicle during a period when thefirst decelerating control is performed, (i) the setting device sets asecond target position on the basis of the detected second sign objectand (ii) the supporting device performs a second decelerating controlfor decelerating the vehicle to a second target speed before the vehiclereaches the second target position, instead of the first deceleratingcontrol.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram that illustrates a structure of a vehicle in apresent embodiment.

FIG. 2 is a flowchart that illustrates a flow of a driving support.

FIG. 3 is a planar view that illustrates one example of a temporarytarget position.

FIG. 4 is a planar view that illustrates one example of a definitetarget position.

FIG. 5 is a planar view that illustrates one example of a temporarytarget position.

FIG. 6 is a timing chart that illustrates a temporal transition of adeceleration rate and speed of the vehicle when a main decelerationcontrol is performed after a preliminary deceleration control isperformed.

DESCRIPTION OF EMBODIMENTS

Hereinafter, with reference to drawings, one embodiment of the drivingsupport apparatus of the present invention will be described. In thefollowing description, a vehicle 1 to which one embodiment of thedriving support apparatus of the present invention is adapted will bedescribed.

(1) STRUCTURE OF VEHICLE 1

Firstly, with reference to FIG. 1, the structure of the vehicle 1 in thepresent embodiment will be explained. As illustrated in FIG. 1, thevehicle 1 has: a camera 11, an ECU (Electronic Control Unit) 12 that isone example of a “driving support apparatus” in a below describedadditional statement; a brake actuator 13; and a brake apparatus 14.

The camera 11 is an imaging device that is configured to image (capture)an area ahead of the vehicle 1. An image captured by the camera 11(namely, an image that represents a circumstance ahead of the vehicle 1)is outputted from the camera 11 to the ECU 12.

The ECU 12 is configured to control entire operation of the vehicle 1.Especially in the present embodiment, the ECU 12 is configured toperform a driving support for stopping the vehicle 1 at a targetposition. In order to perform the driving support, the ECU 12 includes,as processing blocks that are logically realized in the ECU 12 orprocessing circuits that are physically realized in the ECU 12, an imagerecognizing unit 121, a position setting unit 122 that is one example ofa “setting device” in the below described additional statement and asupporting unit that is one example of a “supporting device” in thebelow described additional statement. The operation of each of the imagerecognizing unit 121, the position setting unit 122 and the supportingunit 123 will be briefly described here, although it is described laterin detail (see FIG. 2 and so on). The image recognizing unit 121 isconfigured to detect a stop sign 21 and a stop line 22 from the imagecaptured by the camera 11. The stop sign 21 is a road sign that requeststhe vehicle 1 to stop. The stop line 22 is a road mark that is drawn onthe road to represent a position at which the vehicle 1 should stop.Note that the stop sign 21 and the stop line 22 are examples of a “firstsign object” and a “second sign object” in the below describedadditional statement, respectively. The position setting unit 122 isconfigured to set the target position at which the vehicle 1 should stopon the basis of the detection result of the image recognizing unit 121.The supporting unit 123 is configured to control the brake actuator 13to stop the vehicle 1 at the target position.

The brake actuator 13 is configured to control the brake apparatus 14that is configured to brake a non-illustrated wheel in order to apply abraking force to the vehicle 1 under the control of the supporting unit123. As a result, the driving support that is performed by thesupporting unit 123 allows the vehicle 1 to stop at the target positionwithout requiring an operation by the driver. Alternatively, the drivingsupport that is performed by the supporting unit 123 assists anoperation of a brake pedal by the driver so that the vehicle 1 stops atthe target position.

(2) DRIVING SUPPORT PERFORMED BY ECU 12

Next, with reference to FIG. 2, the driving support that is performed bythe ECU 12 will be described. FIG. 2 is a flowchart that illustrates aflow of the driving support that is performed by the ECU 12.

As illustrated in FIG. 2, firstly, the position setting unit 122determines whether or not at least one of the stop sign 21 and the stopline 22 is detected by the image recognizing unit 121 (a step S12). Notethat the camera 11 keeps imaging the area ahead of the vehicle 1 duringa period when the driving support illustrated in FIG. 2 is performed.Thus, the image recognizing unit 121 keeps performing a process ofdetecting the stop sign 21 and the stop line 22 from the image capturedby the camera 11 during the period when the driving support illustratedin FIG. 2 is performed.

As a result of the determination at the step S12, if it is determinedthat both of the stop sign 21 and the stop line 22 are not detected (thestep S12: No), the ECU 12 terminates the driving support illustrated inFIG. 2. When the ECU 12 terminates the driving support illustrated inFIG. 2, the ECU 12 starts the driving support illustrated in FIG. 2again after a predetermined period has elapsed.

On the other hand, as a result of the determination at the step S12, ifit is determined that at least one of the stop sign 21 and the stop line22 is detected (the step S12: Yes), the position setting unit 122determines whether or not a support execution condition is satisfied (astep S13). The support execution condition is a condition that should besatisfied in order to actually start to control the vehicle 1 to stop atthe target position. The support execution condition includes acondition that the vehicle 1 reaches a position at which the detectedstop sign 21 is placed or the detected stop line 22 is drawn within apredetermined time under a condition where the vehicle 1 maintainscurrent speed, for example.

As a result of the determination at the step S13, if it is determinedthat the support execution condition is not satisfied (the step S13:No), the ECU 12 terminates the driving support illustrated in FIG. 2without controlling the vehicle 1 to stop at the target position.

On the other hand, as a result of the determination at the step S13, ifit is determined that the support execution condition is satisfied (thestep S13: Yes), the ECU 12 starts to control the vehicle 1 to stop atthe target position. Specifically, firstly, the position setting unit122 determines whether or not the stop line 22 is detected by the imagerecognizing unit 121 (a step S14).

As a result of the determination at the step S14, if it is determinedthat the stop line 22 is not detected by the image recognizing unit 121(the step S14: No), the image recognizing unit 121 has not detected thestop line 22 yet although the image recognizing unit 121 has alreadydetected the stop sign 21. Note that the stop sign 21 is a threedimensional structure and the stop line 22 is a two dimensional markdrawn on the road, and thus there is a relatively high possibility thatthe camera 11 images the stop sign 21 before the camera 11 images thestop line 22. Alternatively, there is a relatively high possibility thatthe image recognizing unit 121 detects the stop sign 21 before the imagerecognizing unit 121 detects the stop line 22. Thus, the case where theimage recognizing unit 121 has not detected the stop line 22 yetalthough the image recognizing unit 121 has already detected the stopsign 21 occurs to some degree.

In this case, the position setting unit 122 sets a temporal targetposition 31 that represents a position at which the vehicle 1 shouldstop on the basis of the detected stop sign 21 (a step S21). Forexample, there is a high possibility that the stop line 22 that isassociated with the stop sign 21 is drawn in a stop line existing area41 that is set on the road on the basis of the position of the stop sign21. Thus, as illustrated in FIG. 3 that is a planar view illustratingthe stop sign 21 and the stop line 22 placed/drawn near an intersectionat which two road intersect with each other, the position setting unit122 sets the stop line existing area 41 on the basis of the detectedstop sign 21 and then sets the temporary target position 31 at anyposition in the set stop line existing area 41, for example. Forexample, if the detected stop sign 21 is located in the stop lineexisting area 41, the position setting unit 122 may set the temporarytarget position 31 at the position of the detected stop sign 21. Forexample, the position setting unit 122 may set the temporary targetposition 31 at a position that is away from the position of the stopsign 21 toward the near side (namely, toward the vehicle 1) in the stopline existing area 41. For example, the position setting unit 122 mayset the temporary target position 31 at a position that is away from theposition of the stop sign 21 toward the farther side (namely, toward theopposite side of the vehicle 1) in the stop line existing area 41. Notethat FIG. 3 illustrate one example of the temporary target position 31that is set to be away from the position of the stop sign 21 toward thefarther side. Moreover, the stop line existing area 41 is one example ofa “specific area” in the below described additional statement.

The stop line existing area 41 is an area that ranges on the road from afirst position that is away from the detected stop sign 21 by a firstpredetermined distance toward the near side (or toward the farther side)to a second position that is away from the detected stop sign 21 by asecond predetermined distance toward the farther side (or toward thenear side), for example. It is preferable that the position setting unit122 store an information that is necessary for setting the stop lineexisting area 41 on the basis of the detected stop sign 21 (for example,an information relating to the above described first predetermineddistance and the second predetermine distance) in advance.

It is preferable that the position setting unit 122 set the temporarytarget position 31 by using the adjustable (in other words, changeable)stop line existing area 41. For example, there is a possibility that adrawn position at which the stop line 22 associated with the stop sign21 is actually drawn varies depending on a characteristics of the roadon which the stop sign 21 is placed and the stop line 22 is drawn. Eachof a width of the road (or a lane on the road), the number of thelane(s) on the road, a curvature radius of the road and the like is oneexample of the characteristics of the road. Thus, the position settingunit 122 may adjust (change) the stop line existing area 41 on the basisof the characteristics of the road on which the vehicle 1 travels. Forexample, the position setting unit 122 may adjust at least one of a sizeof the stop line existing area 41, a shape (a planar shape on the road)of the stop line existing area 41, a position of an edge part of thestop line existing area 41 and the like. Alternatively, for example,there is a possibility that the drawn position at which the stop line 22associated with the stop sign 21 is actually drawn varies for everycountry. Thus, the position setting unit 122 may adjust the stop lineexisting area 41 depending on which country the vehicle 1 travels.However, the position setting unit 122 may set the temporary targetposition 31 by using the fixed stop line existing area 41.

After the temporary target position 31 is set, the supporting unit 123performs a preliminary deceleration control for decelerating the vehicle1 to stop the vehicle 1 at the temporary target position 31 that is setat the step S21 (a step S22). Namely, the supporting unit 123 performsthe preliminary deceleration control for decreasing the speed of thevehicle 1 to zero before the vehicle 1 reaches the temporary targetposition 31 that is set at the step S21 (in other words, at the timingat which the vehicle 1 reaches the temporary target position 31) (thestep S22). Note that the temporary target position 31 and thepreliminary deceleration control are examples of a “first targetposition” and a “first deceleration control” in the below describedadditional statement.

Specifically, the supporting unit 123 calculates a distance d1 from acurrent position of the vehicle 1 to the temporary target position 31.Then, the supporting unit 123 calculates a required deceleration rate D1that is necessary for the vehicle 1 to stop at the temporary targetposition 31 on the basis of the calculated distance d1 and the currentspeed V1 of the vehicle 1. Note that the supporting unit 123 maycalculate the required deceleration rate D1 by using a formula D1=V1²/d1, if the preliminary deceleration control decelerates the vehicle 1at a constant deceleration rate. Then, the supporting unit 123 controlsthe brake actuator 13 to apply to the vehicle 1 the braking force thatallows the vehicle 1 to decelerate at the calculated requireddeceleration rate D1. As a result, the vehicle 1 decelerates at thecalculated required deceleration rate D1.

During a period when the preliminary deceleration control is performed,the position setting unit 122 determines whether or not the stop line 22that has not detected before now is newly detected by the imagerecognizing unit 121 (a step S23). Here, the position setting unit 122determines whether or not the image recognizing unit 121 newly detectsthe stop line 22 that is drawn on the road to be associated with thestop sign 21 used to calculate the temporary target position 31 at thestep S21.

As a result of the determination at the step S23, if it is determinedthat the stop line 22 is not detected by the image recognizing unit 121(the step S23: No), the supporting unit 123 determines whether or notthe vehicle 1 reaches the temporary target position 31 (a step S24). Asa result of the determination at the step S24, if it is determined thatthe vehicle 1 reaches the temporary target position 31 (the step S24:Yes), the ECU 12 terminates the preliminary deceleration control (a stepS25) and terminates the driving support illustrated in FIG. 2. On theother hand, as a result of the determination at the step S24, if it isdetermined that the vehicle 1 does not reach the temporary targetposition 31 yet (the step S24: No), the ECU 12 continues the preliminarydeceleration control.

On the other hand, as a result of the determination at the step S23, ifit is determined that the stop line 22 is newly detected by the imagerecognizing unit 121 (the step S23: Yes), the position setting unit 122sets a definite target position 32 that represents a position at whichthe vehicle 1 should stop on the basis of the detected stop line 22 (astep S31). Specifically, as illustrated in FIG. 4, the position settingunit 122 sets the definite target position 32 at the position of thedetected stop line 22. However, the position setting unit 122 may setthe definite target position 32 at a position that is away from theposition of the detected stop line 22 toward the near side or thefarther side.

After the definite target position 32 is set, the supporting unit 123performs a main deceleration control for decelerating the vehicle 1 tostop the vehicle 1 at the definite target position 32 that is set at thestep S31 (a step S32). Namely, the supporting unit 123 performs the maindeceleration control for decreasing the speed of the vehicle 1 to zerobefore the vehicle 1 reaches the definite target position 32 that is setat the step S31 (in other words, at the timing at which the vehicle 1reaches the definite target position 32) (the step S22). Note that thedefinite target position 32 and the main deceleration control areexamples of a “second target position” and a “second decelerationcontrol” in the below described additional statement.

Specifically, the supporting unit 123 calculates a distance d2 from thecurrent position of the vehicle 1 to the definite target position 32.Then, the supporting unit 123 calculates a required deceleration rate D2that is necessary for the vehicle 1 to stop at the definite targetposition 32 on the basis of the calculated distance d2 and the currentspeed V2 of the vehicle 1. Note that the supporting unit 123 maycalculate the required deceleration rate D2 by using a formula D2=V2²/d2, if the main deceleration control decelerates the vehicle 1 at aconstant deceleration rate. Then, the supporting unit 123 controls thebrake actuator 13 to apply to the vehicle 1 the braking force thatallows the vehicle 1 to decelerate at the calculated requireddeceleration rate D2. As a result, the vehicle 1 decelerates at thecalculated required deceleration rate D2.

During a period when the main deceleration control is performed, thesupporting unit 123 determines whether or not the vehicle 1 reaches thedefinite target position 32 (a step S34). As a result of thedetermination at the step S34, if it is determined that the vehicle 1reaches the definite target position 32 (the step S34: Yes), the ECU 12terminates the main deceleration control (a step S35) and terminates thedriving support illustrated in FIG. 2. On the other hand, as a result ofthe determination at the step S34, if it is determined that the vehicle1 does not reach the definite target position 32 yet (the step S34: No),the ECU 12 continues the main deceleration control.

On the other hand, as a result of the determination at the step S14, ifit is determined that the stop line 22 is detected by the imagerecognizing unit 121 (the step S14: Yes), the stop line 22 that isnecessary for setting the definite target position 32 is alreadydetected although the temporary target position 31 is not yet set on thebasis of the stop sign 21 (namely, the preliminary deceleration controlis not yet performed). In this case, the ECU 12 starts to perform themain deceleration control without performing the preliminarydeceleration control (the step S31 to the step S35).

(3) TECHNICAL EFFECT

As described above, firstly in the present embodiment, the temporarytarget position 31 is set on the basis of the stop sign 21. The stopsign 21 is the three dimensional structure. Thus, the stop sign 21 isrecognizable more easily from a distance than the stop line 22. Thus, inthe present embodiment, not only the main deceleration control but alsothe preliminary deceleration control are performed, compared to a firstcomparison in which the temporary target position 31 is not set on thebasis of the stop sign 21 (namely, only the definite target position 32is set on the basis of the stop line 22). Namely, in the presentembodiment, the ECU 12 is allowed to control (namely, decelerate) thevehicle 1 by the preliminary deceleration control before the stop line22 is detected. Thus, in the present embodiment, it is possible tosecure more opportunity to control (namely, decelerate) the vehicle 1,compared to the first comparison example, because the preliminarydeceleration control is additionally performed. Moreover, in the presentembodiment, if the stop line 22 is detected during the period when thepreliminary deceleration control is performed by using the temporarytarget position 31, the definite target position 32 is set on the basisof the stop line 22. Thus, in the present embodiment, it is possible toset the definite target position 32 at (or near) the position at whichthe stop line 22 is drawn, compared to a second comparison example inwhich the definite target position 32 is not set on the basis of thestop line 22 (namely, only the temporary target position 31 is set onthe basis of the stop sign 21). Namely, in the present embodiment, it ispossible to appropriately set the definite target position 32, comparedto the second comparison example. As a result, the present embodiment isallowed to balance the calculation of the appropriate target positionthat represents the position at which the vehicle 1 should stop and thesecurement of the opportunity to control the vehicle 1 by thepreliminary deceleration control and the main deceleration control, bysetting the temporary target position 31 and then setting the definitetarget position 32.

Moreover, in the present embodiment, if the stop line 22 is alreadydetected before the preliminary deceleration control is performed (thestep S14 in FIG. 2: Yes), ECU 12 starts to perform the main decelerationcontrol without performing the preliminary deceleration control. Thereis a high possibility that the case where the stop line 22 is alreadydetected before the preliminary deceleration control is performed occurswhen the speed of the vehicle 1 is relatively small. The reason is asfollows. If the stop sign 21 is detected and the stop line 22 is notdetected, there is a possibility that the support execution conditionthat the vehicle 1 reaches the position at which the detected stop sign21 is placed within the predetermined time is not satisfied, because thestop sign 21 is detectable from a distance. In this case, if the speedof the vehicle 1 is relatively small, there is a relatively highpossibility that the stop line 22 is detected before the supportexecution condition that the vehicle 1 reaches the position at which thedetected stop sign 21 is placed within the predetermined time issatisfied, because the vehicle 1 travels relatively slowly. As a result,the case where the stop line 22 is already detected at the timing whenthe support execution condition is satisfied occurs. On the other hand,if the speed of the vehicle 1 is relatively large, there is a relativelyhigh possibility that the support execution condition that the vehicle 1reaches the position at which the detected stop sign 21 is placed withinthe predetermined time is satisfied before the stop line 22 is detected,because the vehicle 1 travels relatively fast. Thus, if the speed of thevehicle 1 is relatively large, there is a high possibility that the maindeceleration control is performed after the preliminary decelerationcontrol is performed. Namely, in the present embodiment, there is a highpossibility that the main deceleration control is performed without thepreliminary deceleration control being performed if the speed of thevehicle 1 is relatively small and the main deceleration control isperformed after the preliminary deceleration control is performed if thespeed of the vehicle 1 is relatively large. As a result, in the presentembodiment, it is possible to reduce a processing load of the ECU 12,compared to a third comparison example in which the preliminarydeceleration control is always performed before the main decelerationcontrol is performed, because the ECU 12 does not necessarily performthe preliminary deceleration control when the speed of the vehicle 1 isrelatively small. Alternatively, the ECU 12 may determine whether or notthe speed of the vehicle 1 is relatively small (for example, smallerthan a predetermined speed) instead of the determination of the step S14in FIG. 2, and then may perform the main deceleration control withoutperforming the preliminary deceleration control if it is determined thatthe speed of the vehicle 1 is relatively small and may perform the maindeceleration control after performing the preliminary decelerationcontrol if it is determined that the speed of the vehicle 1 isrelatively large, in order to surely achieve the technical effect of theprocessing load of the ECU 12 being reduced.

(4) MODIFIED EXAMPLE (4-1) First Modified Example

In the first modified example, as illustrated in FIG. 5, the positionsetting unit 122 sets the temporary target position 31 at edge portionof the stop line existing area 41 that is farthest from the vehicle 1.As a result, as illustrated in FIG. 5, there is a relatively highpossibility that the temporary target position is set at the fartherside from the definite target position 32 (namely, the position of thestop line 22). If the temporary target position is set at the fartherside from the definite target position 32, the required decelerationrate D1 the is necessary for the vehicle 1 to stop at the temporarytarget position 31 is smaller than the required deceleration rate D2 theis necessary for the vehicle 1 to stop at the definite target position32 as illustrated in FIG. 6. As a result, the vehicle 1 firstlydecelerates relatively gently by the preliminary deceleration control,then decelerates relatively rapidly by the main deceleration control andthen stops at the definite target position 32. This deceleration aspectof the vehicle 1 is similar to the deceleration aspect of the vehicle 1that is realized by the driver to operate the brake pedal in order tostop the vehicle 1 at the definite target position 32. This is becausethe driver tends to decelerate the vehicle relatively gently by pedalingthe brake pedal relatively gently at first and then pedal the brakepedal more as the vehicle 1 approaches the definite target position 32more to stop the vehicle 1, when the driver operates the brake pedal inorder to stop the vehicle 1 at the definite target position 32. Thus, inthe first modified example, the preliminarily deceleration control andthe main deceleration control allow the vehicle 1 to decelerate in thedeceleration aspect that reduces an uncomfortable feeling of the driver.

Alternatively, there is a higher possibility that the temporary targetposition is set at the farther side from the definite target position 32in the case where the temporary target position is set at the fartherside than the position of the stop sign 21, compared to the case wherethe temporary target position is set at the position of the stop sign 21or at the near side from the position of the stop sign 21. Thus, even inthe case where the temporary target position is set at the farther sidethan the position of the stop sign 21, it is possible to achieve, tosome degree, the technical effect that the vehicle 1 is allowed todecelerate in the deceleration aspect that reduces an uncomfortablefeeling of the driver.

(4-2) Second Modified Example

In the second modified example, the position setting unit 122 sets thetemporary target position 31 on the basis of a road information relatingto the road on which the vehicle 1 travels, in addition to the stop sign21 detected by the image recognizing unit 121. The road informationincludes an information relating to the road that is useful to estimatethe position of the stop line 22. For example, an information relatingto a shape of an intersection ahead of the stop sign 21 is the usefulinformation for estimating the position of the stop line 22, because thestop line 22 is drawn in accordance with the shape of the intersection.Note that the road information may be obtained by the image recognizingunit 121 from the image captured by the camera 11.

According to the second modified example, there is a higher possibilitythat the temporary target position 31 is set at the position nearer tothe definite target position 32, compared to the case where thetemporary target position 31 is set on the basis of not the roadinformation but the stop sign 21.

Note that the position setting unit 122 may set the temporary targetposition 31 on the basis of the stop sign 21, then may newly set thetemporary target position 31 on the basis of the stop sign 21 and theroad information after the road information is obtained, and then mayset the definite target position 32 on the basis of the stop line 22after the stop line 22 is detected. As a result, the position settingunit 122 is allowed to update the temporary target position 31 so thatnew temporary target position 31 that is estimated to be closer to theposition of the actual stop line 22 is set. Alternatively, the positionsetting unit 122 may set the temporary target position 31 on the basisof the stop sign 21, then may newly set the temporary target position 31on the basis of the stop sign 21 and newly detected sign object afterthe sign object that requests the vehicle 1 to stop is newly detected,and then may set the definite target position 32 on the basis of thestop line 22 after the stop line 22 is detected, in addition to orinstead of using the road information, in order to newly set thetemporary target position 31 that is closer to the position of theactual stop line 22. Namely, the position setting unit 122 may set aplurality of temporary target positions 31 (especially, a plurality oftemporary target positions 31 each of which increases possibility thatthe temporary target position 31 is closer to the definite targetposition 32 than ever before) on the basis of a plurality of anyparameters.

(4-3) Another Modified Example

In the above described description, the position setting unit 122 setsthe temporary target position 31 at any position in the stop lineexisting area 41 that is set on the basis of a sign position at whichthe stop sign 21 is placed. However, the position setting unit 122 mayset the temporary target position 31 without using the stop lineexisting area 41.

In the above described description, the image recognizing unit 121detects the stop sign 21 that requests the vehicle 1 to stop. However,the image recognizing unit 121 may detect any sign object (for example,the road sign, the road mark, any structural object and the like) thatrequests the vehicle 1 to stop, in addition to or instead of the stopsign 21. Each of the signal having a light color that requests thevehicle 1 to stop (for example, the read signal or the yellow signal inJapan), the road sign other than the stop sign 21 that requests thevehicle 1 to stop, the road mark having text characters (for example,the text characters such as “STOP”) drawn on the road at the near sideof the stop line 22, a crash barrier or a guard rail (especially, at aT-shaped intersection) and the like is one example of the sign objectthat requests the vehicle 1 to stop. Even in this case, the abovedescribed technical effect can be achieved if the temporary targetposition 31 is set on the basis of the detected sign object. Namely,since the temporary target position 31 is still set on the basis of thesign object, and thus it is possible to secure more opportunity tocontrol (namely, decelerate) the vehicle 1, because the preliminarydeceleration control is additionally performed. Note that any signobject that requests the vehicle 1 to stop is one example of the “firstsign object” in the below described additional statement.

In the above described description, the image recognizing unit 121detect the stop line 22 that requests the vehicle 1 to stop. However,the image recognizing unit 121 may detect any sign object (for example,the road sign, the road mark, any structural object and the like) thatrepresents the position at which the vehicle 1 should stop, in additionto or instead of the stop line 22. Each of a crosswalk, a road mark thatrepresents a stop-restricted area, a road sign that indicates theposition of the stop line 22 and that is placed at the side of the roadand the like is one example of the sign object that represents theposition at which the vehicle 1 should stop. Even in this case, theabove described technical effect can be achieved if the definite targetposition 32 is set on the basis of the detected sign object. Namely,since the definite target position 32 is still set on the basis of thesign object, and thus it is possible to appropriately set the definitetarget position 32. Note that any sign object that represents theposition at which the vehicle 1 should stop is one example of the“second sign object” in the below described additional statement.

In the above described description, the deceleration rate of the vehicle1 is constant during the preliminary deceleration control. However, thesupporting unit 123 may decelerate the vehicle 1 so that thedeceleration rate of the vehicle 1 varies during the preliminarydeceleration control. For example, the supporting unit 123 maydecelerate the vehicle 1 so that the deceleration rate of the vehicle 1varies during the preliminary deceleration control in the same manner asthe deceleration rate of the vehicle 1 that is realized by the driver tooperate the brake pedal (for example, an average of the decelerationrates that are realized by many drivers to operate the brake pedal). Thedeceleration rate of the vehicle 1 also varies during the maindeceleration control, as with the preliminary deceleration control.

The ECU 12 may perform a driving support for decelerating the vehicle 1to a target speed (for example, 5 km/h to 10 km/h) before the vehicle 1reaches the target position, in addition to or instead of the drivingsupport for stopping the vehicle 1 at the target position. Namely, theECU 12 may perform the driving support for decelerating the vehicle 1 sothat the speed of the vehicle 1 is equal to the target speed at thetiming when the vehicle 1 reaches the target position. Note that thedriving support for decelerating the vehicle 1 to the target speedbefore the vehicle 1 reaches the target position is equivalent to thedriving support for stopping the vehicle 1 at the target position, ifthe target speed is zero.

It is preferable that the target position (namely, the temporary targetposition 31 and the definite target position 32) be set by the abovedescribed operation even in the case where the ECU 12 performs thedriving support for decelerating the vehicle 1 to the target speedbefore the vehicle 1 reaches the target position. Namely, it ispreferable that the ECU 12 firstly perform the driving support fordecelerating the vehicle 1 to a first target speed before the vehicle 1reaches the temporary target position 31 and then perform the drivingsupport for decelerating the vehicle 1 to a second target speed that issame as or different from the first target speed before the vehicle 1reaches the definite target position 32. As a result, the abovedescribed technical effect can be achieved even in the case where theECU 12 performs the driving support for decelerating the vehicle 1 tothe target speed before the vehicle 1 reaches the target position.

If the ECU 12 performs the driving support for decelerating the vehicle1 to the target speed before the vehicle 1 reaches the target position,the image recognizing unit 121 may detect any sign object (typically, astructural object) that requests the vehicle 1 to decelerate, inaddition to or instead of the stop sign 21 (alternatively, any signobject that requests the vehicle 1 to stop). Each of the road sign (orthe road mark) that requests the vehicle 1 to slow down, the road sign(or the road mark) that indicates the presence of the school and thelike is one example of any sign object that requests the vehicle 1 todecelerate. Even in this case, the above described technical effect canbe achieved if the temporary target position 31 is set on the basis ofthe detected sign object.

If the ECU 12 performs the driving support for decelerating the vehicle1 to the target speed before the vehicle 1 reaches the target position,the image recognizing unit 121 may detect any sign object thatrepresents a position at which the vehicle 1 should completedecelerating, in addition to or instead of the stop line 22(alternatively, any sign object that represents the position at whichthe vehicle 1 should stop). Even in this case, the above describedtechnical effect can be achieved if the definite target position 32 isset on the basis of the detected sign object.

In the above described description, the stop sign 21 and the stop line22 are detected from the image that represents the circumstance ahead ofthe vehicle 1 and that is captured by the camera 11. However, the stopsign 21 and the stop line 22 may be detected by another method. Forexample, the stop sign 21 and the stop line 22 may be detected by adetection result of a radar or a LIDAR (Light Detection and Ranging).

(5) ADDITIONAL STATEMENT

Relating to the above described embodiment, following additionalstatements will be disclosed.

(5-1) Additional Statement 1

A driving support apparatus according to the additional statement 1 is adriving support apparatus having: a setting device that is configured toset a first target position on the basis of a detected first signobject, if the first sign object is detected ahead of a vehicle, thefirst sign object requesting the vehicle to stop or decelerate; and asupporting device that is configured to perform a first decelerationcontrol for decelerating the vehicle to a first target speed before thevehicle reaches the first target position, if a second sign object thatis placed to be associated with the first sign object and thatrepresents a position at which the vehicle should complete stopping ordecelerating is detected ahead of the vehicle during a period when thefirst decelerating control is performed, (i) the setting device sets asecond target position on the basis of the detected second sign objectand (ii) the supporting device performs a second decelerating controlfor decelerating the vehicle to a second target speed before the vehiclereaches the second target position, instead of the first deceleratingcontrol.

A driving support apparatus according to the additional statement 1 maybe a driving support apparatus having a controller, the controller isprogrammed to: set a first target position on the basis of a detectedfirst sign object, if the first sign object is detected ahead of avehicle, the first sign object requesting the vehicle to stop ordecelerate; and to perform a first deceleration control for deceleratingthe vehicle to a first target speed before the vehicle reaches the firsttarget position, if a second sign object that is placed to be associatedwith the first sign object and that represents a position at which thevehicle should complete stopping or decelerating is detected ahead ofthe vehicle during a period when the first decelerating control isperformed, (i) the controller is programmed to set a second targetposition on the basis of the detected second sign object and (ii) thecontroller is programmed to perform a second decelerating control fordecelerating the vehicle to a second target speed before the vehiclereaches the second target position, instead of the first deceleratingcontrol.

The driving support apparatus according to the additional statement 1firstly sets the first target position on the basis of the first signobject such as a road sign and a signal. Thus, the driving supportapparatus according to the additional statement 1 is allowed to controlthe vehicle by the first deceleration control before the second signobject is detected. As a result, the driving support apparatus accordingto the additional statement 1 is allowed to secure more opportunity tocontrol the vehicle by the first deceleration control and the seconddeceleration control, compared to a driving support apparatus in a firstcomparison example that does not set the first target position on thebasis of the first sign object (namely, that sets only the second targetposition on the basis of the second sign object), because the drivingsupport apparatus according to the additional statement 1 is allowed toperform not only the second deceleration control but also the firstdeceleration control. Moreover, the driving support apparatus accordingto the additional statement 1 sets the second target position on thebasis of the second sign object, if the second sign object such as astop line is detected during the period when the first decelerationcontrol using the first target position is performed. Thus, the drivingsupport apparatus according to the additional statement 1 is allowed toset the second target position at or near a position at which thevehicle should complete stopping or decelerating, compared to a drivingsupport apparatus in a second comparison example that does not set thesecond target position on the basis of the second sign object (namely,that sets only the first target position on the basis of the first signobject). Namely, the driving support apparatus according to theadditional statement 1 is allowed to appropriately set the second targetposition. As a result, the driving support apparatus according to theadditional statement 1 is allowed to balance the calculation of theappropriate target position that represents the position at which thevehicle should complete stopping or decelerating and the securement ofthe opportunity to control the vehicle by the first deceleration controland the second deceleration control, by setting the temporary firsttarget position and then setting the definite second target position.

Note that the first target speed may be same as or different from thesecond target speed. At least one of the first target speed and thesecond target speed may be zero or larger than zero.

(5-2) Additional Statement 2

A driving support apparatus according to the additional statement 2 isthe driving support apparatus according to the additional statement 1,wherein a deceleration rate of the vehicle by the first deceleratingcontrol is smaller than a deceleration rate of the vehicle by the seconddecelerating control.

The driving support apparatus according to the additional statement 2allows the vehicle to decelerate relatively gently at a relatively smalldeceleration rate and then to decelerate relatively rapidly at arelatively large deceleration rate. This deceleration aspect of thevehicle is similar to the deceleration aspect of the vehicle that isrealized by a driver to operate a brake pedal in order to decelerate thevehicle to the target speed before the vehicle reaches the targetposition. Thus, the driving support apparatus according to theadditional statement 2 is allowed to decelerate the vehicle in thedeceleration aspect that reduces an uncomfortable feeling of the driver.

(5-3) Additional Statement 3

A driving support apparatus according to the additional statement 3 isthe driving support apparatus according to the additional statement 1 or2, wherein the setting device sets the first target position at aposition that is farther than the detected first sign object from thevehicle.

A driving support apparatus according to the additional statement 3 maybe the driving support apparatus according to the additional statement 1or 2, wherein the controller is programmed to set the first targetposition at a position that is farther than the detected first signobject from the vehicle.

The driving support apparatus according to the additional statement 3 isallowed to increase the possibility that the first target position isset at a position that is farther than the second target position. As aresult, there is an increased possibility that the deceleration rate ofthe vehicle by the first decelerating control is smaller than thedeceleration rate of the vehicle by the second decelerating control.Therefore, the driving support apparatus according to the additionalstatement 3 is allowed to decelerate the vehicle in the decelerationaspect that reduces the uncomfortable feeling of the driver, as with thedriving support apparatus according to the additional statement 2.

(5-4) Additional Statement 4

A driving support apparatus according to the additional statement 4 isthe driving support apparatus according to any one of the additionalstatements 1 to 3, wherein the setting device sets the first targetposition at an area portion that is one portion of a specific area andthat is the farthest portion from the vehicle, the specific area is setin advance on the basis of the detected first sign object as an area inwhich the second sign object is possibly placed to be associated withthe detected first sign object.

A driving support apparatus according to the additional statement 4 maybe the driving support apparatus according to any one of the additionalstatements 1 to 3, wherein the controller is programmed to set the firsttarget position at an area portion that is one portion of a specificarea and that is the farthest portion from the vehicle, the specificarea is set in advance on the basis of the detected first sign object asan area in which the second sign object is possibly placed to beassociated with the detected first sign object.

The driving support apparatus according to the additional statement 4 isallowed to increase the possibility that the first target position isset at a position that is farther than the second target position. As aresult, there is an increased possibility that the deceleration rate ofthe vehicle by the first decelerating control is smaller than thedeceleration rate of the vehicle by the second decelerating control.Therefore, the driving support apparatus according to the additionalstatement 4 is allowed to decelerate the vehicle in the decelerationaspect that reduces the uncomfortable feeling of the driver, as with thedriving support apparatus according to the additional statement 2.

(5-5) Additional Statement 5

A driving support apparatus according to the additional statement 5 isthe driving support apparatus according to any one of the additionalstatements 1 to 4, wherein the supporting device starts to perform thesecond deceleration control on the condition that the second sign objectis detected during the period when the first deceleration control isperformed, if a speed of the vehicle is larger than a predeterminedspeed, and the supporting device starts to perform the seconddeceleration control on the condition that the second sign object isdetected regardless of the first deceleration control being performed ornot, if the speed of the vehicle is smaller than the predeterminedspeed.

A driving support apparatus according to the additional statement 5 maybe the driving support apparatus according to any one of the additionalstatements 1 to 4, wherein the controller is programmed to start toperform the second deceleration control on the condition that the secondsign object is detected during the period when the first decelerationcontrol is performed, if a speed of the vehicle is larger than apredetermined speed, and the controller is programmed to start toperform the second deceleration control on the condition that the secondsign object is detected regardless of the first deceleration controlbeing performed or not, if the speed of the vehicle is smaller than thepredetermined speed.

The driving support apparatus according to the additional statement 5 isallowed to reduce a processing load of the driving support apparatus,because the driving support apparatus does not need to perform the firstdeceleration control when the speed of the vehicle is smaller than thepredetermined speed.

At least one portion of the feature in the above described embodimentmay be eliminated or modified accordingly. At least one portion of thefeature in the above described embodiments may be combined with anotherone of the above described embodiments.

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2017-144189, filed on Jul. 26,2017, the entire contents of which are incorporated herein by reference.In addition, the entire contents of the above described PatentLiteratures 1 and 2 are incorporated herein by reference.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the inventionand the concepts contributed by the inventor to furthering the art, andare to be construed as being without limitation to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although the embodiments of the presentinvention have been described in detail, it should be understood thatthe various changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention. A drivingsupport apparatus, which involve such changes, are also intended to bewithin the technical scope of the present invention.

REFERENCE SIGNS LIST

-   -   1 vehicle    -   11 camera    -   12 ECU    -   121 image recognizing unit    -   122 position setting unit    -   123 supporting unit    -   13 brake actuator    -   14 brake apparatus    -   21 stop sign    -   22 stop line    -   31 temporary target position    -   32 definite target position    -   41 stop line existing area

The invention claimed is:
 1. A driving support system for a vehiclecomprising: a camera that captures an image of an area ahead of thevehicle; a brake actuator that controls a brake without requiring anoperation by a driver; a controller programmed to: detect at least oneof a stop sign and a stop line drawn on a road surface in the area aheadof the vehicle based on the image captured by the camera; determinewhether the stop line has been detected, wherein based upon the stopsign being detected and the stop line not being detected, (i) set atemporary target position that represents a position at which thevehicle should stop on a basis of a position of the detected stop signand (ii) control the brake actuator to perform a preliminarydeceleration control for decelerating the vehicle to a first targetspeed before the vehicle reaches the temporary target position, whereinbased upon the stop line being detected during a period when thepreliminary deceleration control is being performed, (i) set a definitetarget position that represents a position at which the vehicle shouldstop on a basis of a position of the detected stop line and (ii) controlthe brake actuator to perform a main deceleration control fordecelerating the vehicle to a second target speed before the vehiclereaches the definite target position, instead of the preliminarydeceleration control, wherein the controller is programmed to set thetemporary target position based on both the position of the detectedstop sign and based on a road information relating to the road on whichthe vehicle travels.
 2. The driving support system according to claim 1,wherein a deceleration rate of the vehicle by the preliminarydeceleration control is smaller than a deceleration rate of the vehicleby the main deceleration control.
 3. The driving support systemaccording to claim 1, wherein the controller is programmed to set thetemporary target position at a position that is farther than thedetected stop sign from the vehicle.
 4. The driving support apparatusaccording to claim 1, wherein the controller is programmed to set a stopline existing area on the basis of the position of the detected stopsign, wherein the stop line existing area is an area that ranges on theroad from a first position that is further away from the vehicle thanthe detected sign to a second position that is closer to the vehiclethan the detected sign, so that the detected sign is located inside thestop line existing area and between the first position and the secondposition, wherein the temporary target position is located in the stopline existing area.
 5. The driving support apparatus according to claim4, wherein the controller sets the temporary target position at an edgeportion of the stop line existing area that corresponds with the firstposition.
 6. The driving support apparatus according to claim 1, whereinthe stop sign may include any three-dimensional structural object thatrequests the vehicle to stop.
 7. A vehicle including electronic controlunit having a processing circuit, programmed to: detect at least one ofa stop sign and a stop line drawn on a road surface in an area ahead ofthe vehicle; determine whether the stop line has been detected, whereinbased upon the stop sign being detected and the stop line not beingdetected, (i) set a temporary target position that represents a positionat which the vehicle should stop on a basis of a position of thedetected stop sign and (ii) perform a preliminary deceleration controlfor decelerating the vehicle to a first target speed before the vehiclereaches the temporary target position, wherein based upon the stop linebeing detected during a period when the preliminary deceleration controlis being performed, (i) set a definite target position that represents aposition at which the vehicle should stop on a basis of a position ofthe detected stop line and (ii) perform a main deceleration control fordecelerating the vehicle to a second target speed before the vehiclereaches the definite target position, instead of the preliminarydeceleration control, wherein the electronic control unit is programmedto set the temporary target position based on both the position of thedetected stop sign and based on a road information relating to the roadon which the vehicle travels.